Is a cortical focus driving a cortico-thalamic circuit in human absence epilepsy?

Abstract

Event Abstract Back to Event Is a cortical focus driving a cortico-thalamic circuit in human absence epilepsy? Pauly Ossenblok1*, Bert Kornips1, Disha Gupta1, 2, Petra Van Houdt1 and Gilles Van Luijtelaar2 1 SLU, Division of Biometry and Systems Analysis, Sweden 2 Radboud University, Netherlands Aim: To describe the cortical cortico-thalamic circuit involvement during the evolvement of MEG spike-and-wave discharges (SWDs) in order to identify a focal cortical onset zone in human absence epilepsy. Methods: MEG recordings were performed for 20 patients (6-15 years of age) with absence seizures, ranging from patients with typical childhood absence epilepsy, who can be treated quite successfully with anti-epileptics, to more complex atypical forms and children who had absences and complex partial clinical features. For each seizure of these children non-linear association analysis was performed for time windows moving through the SWDs present in the MEG. Next, the cluster coefficients were calculated for all significant associations (>0.95) for each MEG sensor based on the graph theory (1). Results: Studying in detail the changes in time and space of the cluster values revealed cortical node activity preceding the first visible spike of the SWDs and in the "build up" period towards the generalized 3 Hz SWDs. The latter showed, like in the study of Westmijse et al. (2), a recurrent pattern of focal regional activity during the spikes alternated by generalized activity during the slow-wave phase of the SWDs, indicating most likely the involvement of a cortico-thalamic network. The results indicate a focal cortical onset zone that differs for the clinically distinct patient populations, whereas the activity underlying the generalized SWDs seems to share a common network during the evolvement of these discharges for all patients studied. Conclusion: The cluster analysis method enables the study of the distinct phases of the SWDs in time and space, which is helpful in identifying the driving cortical node of these discharges. This information can be very helpful for diagnoses and successful treatment of children with absence epilepsy. Acknowledgments: Funded by the Dutch Organization for Scientific Research (NWO).